A preparation method of p-tert-butylbenzoic acid and p-tert-butylbenzoic acid

Abstract

The present invention provides a method for preparing p-tert-butylbenzoic acid, the method comprising: selecting a cobalt salt and a chromium salt of a set ratio to dissolve in an appropriate amount of solvent to obtain a precursor solution of a corresponding metal salt; hydrothermally reacting the precursor solution with an organic ligand to obtain a metal-organic framework structure; chemically depositing a support material on the surface of the metal-organic framework structure, Cu nano-metal particles are laid on the support material to obtain an initial metal-organic framework catalyst, and the initial metal-organic framework catalyst is washed and dried to obtain a metal-organic framework catalyst; the metal-organic framework catalyst and p-tert-butyltoluene are added to a reactor, oxygen is passed through, a crude p-tert-butylbenzoic acid product is obtained, and the crude p-tert-butylbenzoic acid product is refined to obtain a finished p-tert-butylbenzoic acid product. The present invention solves the problem of low conversion efficiency when preparing p-tert-butylbenzoic acid in the prior art.

Description

Technical Field

[0001] The invention relates to the technical field of p-tert-butylbenzoic acid production, and in particular to a p-tert-butylbenzoic acid preparation method and p-tert-butylbenzoic acid. Background Art

[0002] p-tert-butylbenzoic acid (PTBA) is an important organic synthesis intermediate, mainly used as a lubricant additive, alloy preservative and polypropylene nucleating agent, etc. It is also widely used in chemical synthesis, cosmetics and flavors and fragrances. At present, the main methods for synthesizing PTBA are electrochemical oxidation, high-temperature gas phase oxidation and low-temperature liquid phase oxidation, which mainly use catalysts to promote the activation of oxygen and catalyze the reaction process. In the oxidation reaction, the oxygen molecules in the air are activated and react with tert-butyltoluene to finally produce p-tert-butylbenzoic acid.

[0003] Metal-Organic Frameworks (MOFs) are a new type of three-dimensional porous structure materials composed of metal ions or metal clusters and organic ligands through coordination. The characteristics of MOFs materials include extremely high specific surface area, rich pore structure, adjustable pore size and good stability. These characteristics make it have application prospects in catalyzing the synthesis of p-tert-butylbenzoic acid from p-tert-butyltoluene.

[0004] However, during the reaction, the metal center of the metal organic framework material may undergo a cycle of oxidation and reduction reactions, resulting in a decrease in the activity of the metal center. For example, chromium ions may be oxidized to Cr 6+ , and dissolution or formation of inactive metal oxides occurs, thereby reducing the catalytic activity and affecting the catalytic efficiency, resulting in low conversion efficiency of tert-butylbenzoic acid. Summary of the invention

[0005] In view of this, the object of the present invention is to provide a method for preparing p-tert-butylbenzoic acid, aiming to solve the problem of low conversion efficiency when preparing p-tert-butylbenzoic acid in the method for preparing p-tert-butylbenzoic acid in the prior art.

[0006] The embodiment of the present invention is implemented as follows:

[0007] A method for preparing p-tert-butylbenzoic acid, characterized in that the method comprises:

[0008] Selecting a set ratio of cobalt salt and chromium salt and dissolving them in a suitable amount of solvent to obtain a precursor solution of the corresponding metal salt;

[0009] At a set reaction temperature and pH value, the precursor solution is hydrothermally reacted with the organic ligand to obtain a metal-organic framework structure;

[0010] Chemically depositing a support material on the surface of the metal-organic framework structure, using a Cu salt as a metal precursor, dissolving it in a solvent to obtain a Cu salt solution, and immersing the metal-organic framework structure in the Cu salt solution;

[0011] After the impregnation is completed, the impregnated material is reduced to reduce the Cu ions in the Cu salt to nano-metal particles to obtain an initial metal-organic framework catalyst, and the initial metal-organic framework catalyst is washed and dried to obtain a metal-organic framework catalyst;

[0012] A metal-organic framework catalyst and p-tert-butyltoluene are added into a reaction kettle, oxygen is introduced to obtain a crude p-tert-butylbenzoic acid, and the crude p-tert-butylbenzoic acid is refined to obtain a finished p-tert-butylbenzoic acid.

[0013] Furthermore, in the above-mentioned method for preparing p-tert-butylbenzoic acid, the molar ratio of the cobalt salt to the chromium salt is (1-3): (1-2).

[0014] Furthermore, in the above-mentioned method for preparing p-tert-butylbenzoic acid, the temperature of the hydrothermal reaction is 155° C. to 165° C., and the pH value of the hydrothermal reaction is 2 to 3.

[0015] Furthermore, in the above-mentioned method for preparing p-tert-butylbenzoic acid, the organic ligand is potassium hydrogen terephthalate.

[0016] Furthermore, in the above-mentioned method for preparing p-tert-butylbenzoic acid, the supporting material is silicon dioxide, activated carbon or aluminum oxide.

[0017] Furthermore, in the above-mentioned method for preparing p-tert-butylbenzoic acid, deionized water or ethanol is used.

[0018] Furthermore, in the above-mentioned method for preparing p-tert-butylbenzoic acid, the amount of the metal-organic framework catalyst used is 0.3% to 0.5%.

[0019] Furthermore, in the above-mentioned method for preparing p-tert-butylbenzoic acid, the oxygen flow rate is 150mL / min to 200mL / min.

[0020] Furthermore, in the above-mentioned method for preparing p-tert-butylbenzoic acid, the step of refining the crude p-tert-butylbenzoic acid to obtain the finished p-tert-butylbenzoic acid comprises:

[0021] The crude p-tert-butylbenzoic acid is added to toluene, dissolved and filtered, the filtered mother liquor is cooled and crystallized, centrifuged and dried, and washed with p-tert-butyltoluene to obtain the p-tert-butylbenzoic acid fine product.

[0022] Another object of the present invention is to provide p-tert-butylbenzoic acid, which is prepared by the above-mentioned p-tert-butylbenzoic acid preparation method.

[0023] Compared with the prior art: In the preparation of the metal organic framework catalyst, the embodiment of the present invention adopts the method of cobalt and chromium doping to form a metal center, and the two can work synergistically to improve the stability of the metal center. In addition, the doped metal can enhance the redox performance of the metal organic framework structure and reduce the possibility of metal dissolution and deactivation. In addition, copper is loaded on the surface of the metal organic framework structure in the form of nanoparticles. Metal nanoparticles usually have a large specific surface area and high reaction activity. Especially in surface catalytic reactions, they can provide abundant active sites, which help to enhance the rate of the catalytic reaction. The metal center provides the necessary electronic and structural support. The two can work synergistically to further accelerate the reaction rate, and have high selectivity to avoid the occurrence of side reactions. The problem of low conversion efficiency when preparing p-tert-butylbenzoic acid in the prior art is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a flow chart of a method for preparing p-tert-butylbenzoic acid according to one embodiment of the present invention; DETAILED DESCRIPTION

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0027] In addition, the term "and / or" as used herein includes any and all combinations of one or more related listed items. In the detailed description and claims, a list of items connected by the term "one of" may mean any of the listed items. For example, if items A and B are listed, the phrase "one of A and B" means only A or only B. In another example, if items A, B, and C are listed, the phrase "one of A, B, and C" means only A; only B; or only C. Item A may contain a single element or multiple elements. Item B may contain a single element or multiple elements. Item C may contain a single element or multiple elements. In the detailed description and claims, a list of items connected by the terms "at least one of", "at least one of" or other similar terms may mean any combination of the listed items. For example, if items A and B are listed, the phrase "at least one of A and B" or "at least one of A or B" means only A; only B; or A and B. In another example, if items A, B, and C are listed, the phrase "at least one of A, B, and C" or "at least one of A, B, or C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C. Item A may include a single element or multiple elements. Item B may include a single element or multiple elements. Item C may include a single element or multiple elements.

[0028] The present invention aims at the problem of low conversion efficiency in the current preparation of p-tert-butylbenzoic acid, and proposes a method for preparing p-tert-butylbenzoic acid. Figure 1 , wherein the method comprises:

[0029] Step S10, selecting a set ratio of cobalt salt and chromium salt and dissolving them in a proper amount of solvent to obtain a precursor solution of the corresponding metal salt.

[0030] Among them, the corresponding cobalt salt and chromium salt are selected and dissolved together in an appropriate amount of solvent to obtain a precursor solution of the corresponding metal salt. For example, the chromium salt can be Cr(NO3)3 and the cobalt salt can be Co(NO3)2; the solvent can be deionized water or ethanol, and the ratio of cobalt salt to chromium salt is (1-3):(1-2).

[0031] Step S11, at a set reaction temperature and pH value, a precursor solution and an organic ligand are subjected to a hydrothermal reaction to obtain a metal-organic framework structure.

[0032] In the process of synthesizing the metal-organic framework structure, the appropriate reaction temperature and pH value are maintained. The precursor solution of the metal salt reacts with the organic ligand to form the metal-organic framework structure by hydrothermal method; for example, the temperature of the hydrothermal reaction is 155°C to 165°C, the pH value of the hydrothermal reaction is 2 to 3, and the organic ligand is potassium hydrogen terephthalate.

[0033] Step S12, chemically depositing a support material on the surface of the metal-organic framework structure, using a Cu salt as a metal precursor, dissolving it in a solvent to obtain a Cu salt solution, and immersing the metal-organic framework structure in the Cu salt solution.

[0034] Among them, Cu salt is used as a metal precursor, such as copper nitrate, which is dissolved in a solvent to obtain a Cu salt solution, which is used as a support material for chemical deposition on the surface of the metal-organic framework structure, such as silicon dioxide, activated carbon or aluminum oxide. The metal-organic framework structure is immersed in the Cu salt solution to load the metal onto the support material.

[0035] Step S13, after the impregnation is completed, the impregnated material is reduced to reduce the Cu ions in the Cu salt into nano-metal particles to obtain an initial metal-organic framework catalyst, and the initial metal-organic framework catalyst is washed and dried to obtain a metal-organic framework catalyst.

[0036] Among them, the reduction method is used to form metal nanoparticles, and the nanometal particles are loaded on the surface or pores of the metal-organic framework, which needs to be repeatedly washed to remove the unreacted reducing agent and solvent. Then, the metal-organic framework catalyst is obtained by drying under vacuum conditions.

[0037] Step S14, adding the metal-organic framework catalyst and p-tert-butyltoluene into a reaction kettle, introducing oxygen to obtain a crude p-tert-butylbenzoic acid, and refining the crude p-tert-butylbenzoic acid to obtain a finished p-tert-butylbenzoic acid.

[0038] Among them, under the action of the metal-organic framework catalyst, the oxygen molecules are first adsorbed and activated. The activated oxygen molecules generate active oxygen species through coordination with the catalyst, and the oxidizing species attack the methyl group of tert-butyltoluene. After a series of oxidation processes, tert-butylbenzoic acid is finally obtained.

[0039] In addition, after the oxidation reaction, the crude product may contain some unreacted p-tert-butyltoluene, catalyst residues and by-products. In order to obtain pure p-tert-butylbenzoic acid, the crude p-tert-butylbenzoic acid is added to toluene, dissolved and filtered, the filtered mother liquor is cooled and crystallized, centrifuged and dried, and washed with p-tert-butyltoluene to obtain the p-tert-butylbenzoic acid fine product.

[0040] On the other hand, the present invention also provides a p-tert-butylbenzoic acid, which is prepared by the above-mentioned p-tert-butylbenzoic acid preparation method.

[0041] In order to facilitate understanding of the present invention, several embodiments of the present invention are provided below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0042] Example 1

[0043] Select a cobalt salt and a chromium salt in a ratio of 3:2 and dissolve them in an appropriate amount of solvent to obtain a precursor solution of a metal salt with a concentration of 0.1 M;

[0044] At a reaction temperature of 160°C and a pH value of 3, the precursor solution was hydrothermally reacted with potassium hydrogen terephthalate at a ratio of 1:1 to obtain a metal-organic framework structure;

[0045] Chemically depositing activated carbon on the surface of the metal-organic framework structure, using Cu salt as a metal precursor, dissolving it in a solvent to obtain a 0.1M Cu salt solution, and immersing the metal-organic framework structure in the Cu salt solution;

[0046] After the impregnation is completed, the impregnated material is reduced to reduce the Cu ions in the Cu salt to nano-metal particles to obtain an initial metal-organic framework catalyst, and the initial metal-organic framework catalyst is washed and dried to obtain a metal-organic framework catalyst;

[0047] A metal-organic framework catalyst in an amount of 0.3% of the raw material and p-tert-butyltoluene are added to a reactor, oxygen is introduced at a flow rate of 150 mL / min to obtain a crude p-tert-butylbenzoic acid, and the crude p-tert-butylbenzoic acid is refined to obtain a finished p-tert-butylbenzoic acid.

[0048] Example 2

[0049] This embodiment also proposes a method for preparing p-tert-butylbenzoic acid. The difference between the method for preparing p-tert-butylbenzoic acid proposed in this embodiment and the method for preparing p-tert-butylbenzoic acid proposed in Example 1 is that:

[0050] The ratio of cobalt salt to chromium salt is 1:1.5.

[0051] Example 3

[0052] This embodiment also proposes a method for preparing p-tert-butylbenzoic acid. The difference between the method for preparing p-tert-butylbenzoic acid proposed in this embodiment and the method for preparing p-tert-butylbenzoic acid proposed in Example 1 is that:

[0053] The ratio of cobalt salt to chromium salt is 1:2.

[0054] Example 4

[0055] This embodiment also proposes a method for preparing p-tert-butylbenzoic acid. The difference between the method for preparing p-tert-butylbenzoic acid proposed in this embodiment and the method for preparing p-tert-butylbenzoic acid proposed in Example 1 is that:

[0056] The ratio of cobalt salt to chromium salt is 2:1.

[0057] Example 5

[0058] This embodiment also proposes a method for preparing p-tert-butylbenzoic acid. The difference between the method for preparing p-tert-butylbenzoic acid proposed in this embodiment and the method for preparing p-tert-butylbenzoic acid proposed in Example 1 is that:

[0059] The ratio of cobalt salt to chromium salt is 2:1.5.

[0060] Example 6

[0061] This embodiment also proposes a method for preparing p-tert-butylbenzoic acid. The difference between the method for preparing p-tert-butylbenzoic acid proposed in this embodiment and the method for preparing p-tert-butylbenzoic acid proposed in Example 1 is that:

[0062] The ratio of cobalt salt to chromium salt is 3:1.

[0063] Example 7

[0064] This embodiment also proposes a method for preparing p-tert-butylbenzoic acid. The difference between the method for preparing p-tert-butylbenzoic acid proposed in this embodiment and the method for preparing p-tert-butylbenzoic acid proposed in Example 1 is that:

[0065] The ratio of cobalt salt to chromium salt is 3:1.5.

[0066] Example 8

[0067] This comparative example also proposes a method for preparing p-tert-butylbenzoic acid. The difference between the method for preparing p-tert-butylbenzoic acid proposed in this comparative example and the method for preparing p-tert-butylbenzoic acid proposed in Example 1 is that:

[0068] The ratio of cobalt salt to chromium salt is 1:1.

[0069] Example 9

[0070] This comparative example also proposes a method for preparing p-tert-butylbenzoic acid. The difference between the method for preparing p-tert-butylbenzoic acid proposed in this comparative example and the method for preparing p-tert-butylbenzoic acid proposed in Example 1 is that:

[0071] The ratio of cobalt salt to chromium salt is 0:1.

[0072] Example 10

[0073] This comparative example also proposes a method for preparing p-tert-butylbenzoic acid. The difference between the method for preparing p-tert-butylbenzoic acid proposed in this comparative example and the method for preparing p-tert-butylbenzoic acid proposed in Example 1 is that:

[0074] The ratio of cobalt salt to chromium salt is 1:0.

[0075] Embodiment 11

[0076] This comparative example also proposes a method for preparing p-tert-butylbenzoic acid. The difference between the method for preparing p-tert-butylbenzoic acid proposed in this comparative example and the method for preparing p-tert-butylbenzoic acid proposed in Example 1 is that:

[0077] The hydrothermal reaction temperature was 155°C.

[0078] Example 12

[0079] This comparative example also proposes a method for preparing p-tert-butylbenzoic acid. The difference between the method for preparing p-tert-butylbenzoic acid proposed in this comparative example and the method for preparing p-tert-butylbenzoic acid proposed in Example 1 is that:

[0080] The hydrothermal reaction temperature was 165°C.

[0081] Embodiment 13

[0082] This comparative example also proposes a method for preparing p-tert-butylbenzoic acid. The difference between the method for preparing p-tert-butylbenzoic acid proposed in this comparative example and the method for preparing p-tert-butylbenzoic acid proposed in Example 1 is that:

[0083] The pH value is 2.

[0084] Please refer to Table 1 below, which shows the parameters corresponding to the above Examples 1-14 of the present invention and the conversion rate of the prepared tert-butylbenzoic acid product (i.e., the purity of the obtained tert-butylbenzoic acid), as shown in Table 1 below. It should be noted that in order to ensure the accuracy of the experiment, the other process parameters in the above examples are consistent.

[0085] Table 1

[0086]

[0087] Combined with the data of Example 1 to Example 13, it can be seen that the preparation method of p-tert-butylbenzoic acid provided by the present invention can effectively reduce the generation of by-products, improve the yield and selectivity of the reaction, and improve the conversion rate of p-tert-butylbenzoic acid.

[0088] Combined with the data of Examples 1 / 8 / 9, it can be seen that the use of metal doping will give a better synergistic effect, allowing cobalt and chromium to play their respective advantages in the catalyst while maintaining the stability of the metal-organic framework, which helps to obtain better catalytic performance.

[0089] Combined with the data of Examples 1 to 7, it can be seen that the appropriate ratio can better balance the catalytic activity of cobalt and the stability of chromium, while maintaining the structural stability and catalytic activity of the metal-organic framework.

[0090] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing p-tert-butylbenzoic acid, characterized in that: The method comprises: Selecting a set ratio of cobalt salt and chromium salt and dissolving them in a suitable amount of solvent to obtain a precursor solution of the corresponding metal salt; At a set reaction temperature and pH value, the precursor solution is hydrothermally reacted with the organic ligand to obtain a metal-organic framework structure; Chemically depositing a support material on the surface of the metal-organic framework structure, using a Cu salt as a metal precursor, dissolving it in a solvent to obtain a Cu salt solution, and immersing the metal-organic framework structure in the Cu salt solution; After the impregnation is completed, the impregnated material is reduced to reduce the Cu ions in the Cu salt to nano-metal particles to obtain an initial metal-organic framework catalyst, and the initial metal-organic framework catalyst is washed and dried to obtain a metal-organic framework catalyst; A metal-organic framework catalyst and p-tert-butyltoluene are added into a reaction kettle, oxygen is introduced to obtain a crude p-tert-butylbenzoic acid, and the crude p-tert-butylbenzoic acid is refined to obtain a finished p-tert-butylbenzoic acid.

2. The method for preparing p-tert-butylbenzoic acid according to claim 1, wherein The molar ratio of the cobalt salt to the chromium salt is (1-3): (1-2).

3. The method for preparing p-tert-butylbenzoic acid according to claim 1, characterized in that: The temperature of the hydrothermal reaction is 155°C to 165°C, and the pH value of the hydrothermal reaction is 2 to 3.

4. The method for preparing p-tert-butylbenzoic acid according to claim 1, wherein The organic ligand is potassium hydrogen terephthalate.

5. The method for preparing p-tert-butylbenzoic acid according to claim 1, characterized in that: The supporting material is silicon dioxide, activated carbon or aluminum oxide.

6. The method for preparing p-tert-butylbenzoic acid according to claim 1, characterized in that: Deionized water or ethanol.

7. The method for preparing p-tert-butylbenzoic acid according to claim 1, characterized in that: The dosage of the metal-organic framework catalyst is 0.3% to 0.5%.

8. The method for preparing p-tert-butylbenzoic acid according to claim 1, characterized in that: Oxygen flow rate: 150mL / min~200mL / min.

9. The method for preparing p-tert-butylbenzoic acid according to claim 1, characterized in that: The step of refining the crude p-tert-butylbenzoic acid to obtain the finished p-tert-butylbenzoic acid comprises: The crude p-tert-butylbenzoic acid is added to toluene, dissolved and filtered, the filtered mother liquor is cooled and crystallized, centrifuged and dried, and washed with p-tert-butyltoluene to obtain the p-tert-butylbenzoic acid fine product.

10. A p-tert-butylbenzoic acid, characterized in that The tert-butylbenzoic acid is prepared by the method for preparing tert-butylbenzoic acid according to any one of claims 1 to 9.

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